Coil spring tester



y 1939- F. w. GASKINS 2,164,453

- COIL SPRING TESTER Filed Feb. 25. 1937 2 Shets-Sheet 1 "i H I 3 a 7 1a23 #4 SS in as ATTORNEY 4, 1939- F. w. GASKINS 2,164,453

COIL SPRING TESTER Filed Feb. 25, 1937 2 Sheets-Sheet 2 lill lll\ \wnunIII A\ 33 as Ea EZQE :2 M- I ATTORNEYfi Patented July 4, 1939 UNITEDSTATES ATENT OFFICE COIL SPRENG TESTER a corporation of Ohio ApplicationFebruary 25, 1937, Serial No. 127,717

1 Claim.

The type of spring for the testing of which this machine has beendesigned, has certain characteristics which are peculiar to it incomparison with springs of other design. A coil spring may be of theopen or closed coil type. Open coil springs are those in which spaceshave been provided between the coils or convolutions of the springs.Closed coil springs are those in which the convolutions lie against eachother. The open coil spring is the usual one designed and employed foruse by subjecting the opposite ends of the spring to positive pressureswhich bring the ends toward each other, whereas, the closed coil springis primarily designed and employed for use by subjecting the oppositeends of the spring to negative pressures which bring the ends away fromeach other. The closed coil spring is distinguished from an open coilspring in one particular which is inherently functional in that it isthe result of a built-in quality of the spring and has much to do withits performance. I refer to that which is known in the parlance of thedesigner and manufacturer of such springs as initial tension. This isthe tension or pressure 25 with which adjacent coils hug or pressagainst each other, and it is measured or expressed in terms of thenumber of ounces, pounds or other unit of measurement required to bringabout a separation of the adjacent coils when a tension 30 tending topull the opposite ends of the springs apart is placed thereon, whichseparation is commonly known as breaking the coils. However, in themeasuring or testing of such a closed coil spring, there is onecharacteristic which may be stated to be in common with an open coilspring. This the designer calls the rate of the spring. Rate may be saidto be the load required to produce one unit measurement of extension orcompression of the spring. It is obvious that the amount of initialtension which is introduced in a spring may be one factor in thecreation of the total load built into the spring for which the designprovides. With this introduction the aims and purposes of my inventionmay be understood to better advantage.

An object of my invention is to produce a machine for checking ortesting the rates of coil springs for the purpose of determining whethersuch rates are within the limits or tolerances of accuracy.

A further object is to produce a machine for checking or testing therates of coil springs by providing means to establish limits betweenwhich the spring is not only to be tested, but also between which it hasbeen designed to develop its rate, or, between which it has beendesigned to function at a designed rate, or between which it has beendesigned to function at a designed total load.

These and other objects are attained in the 5 spring tester described inthe following specification and illustrated in the acompanying drawings,

in which:

Fig. 1 is an elevation showing the testing machine which embodies myinvention.

Fig. 2 is a side elevation of the machine shown in Fig. 1.

Fig. 3 is an enlarged view, similar to Fig. 1, but showing certaindetails of the machine in section in order that its construction and theoper- 15 ation thereof may be understood to better advantage.

Fig. 4 is an elevational view of a detail showing a means for use in thetesting of open coil or compression springs.

The testing machine I have shown resembles a beam balance or scale, inthat it is provided with a base it which has an upright fulcrum i2 uponwhich a balance arm l3 rests. On one end of the balance arm is anadjustably mounted weight M by means of which the arm is given apreliminary balancing, while on the opposite end of the arm is aslidable weight 15 by means of which the arm is balanced when a springl6 has been placed in position as will be explained. A long anddownwardly extending pointer or indicator- I! is attached to the arm,preferably vertically central with the fulcrum point l8 so that thepoint 9 at the lower end of the indicator will rest, upon proper weightadjustment having been made 5 at the zero (0) mark of a calibrationscale 20 at the lower end of the fulcrum upright l2. An upright plate 2iattached to the right hand end of the base H, is provided with a slot 22within which and by means of which the end 23 of balance armv l3 moves,is guided and limited in its movement. Near end 23 of the arm I3 theweight 24 is hung by means of a link 25 which is provided with anelongated slot 26, the purpose of which slot will be explained, the link25 engages a locating notch 27 in the balance arm to assure definitelocation of the weight when it is supported by the arm.

Beneath a table 28 which supports the structure above described,somewhat as shown, is 1o cated a treadle 29 which is employed to placethe tester in operation. One side of the treadle is connected with alink 30 which is adjustable at 3| as to length, and is connected with arod 32 having sliding mounting in a sleeve 33 mounted in the base H andat the upper end of which is mounted a platform 34. A spring 35 which ismounted between the platform 34 and the base upon the upper end of thesleeve 33 and the projecting upper end of the rod 32, normally holds theplatform elevated so as to lift the weight 24 whereby its link slotfrees the balance arm I3, a stop 36 being clamped in proper adjustedposition on the rod 32 beneath the sleeve 33 to act as a limit of upwardmovement for this purpose. The object of this will be described shortly.

At the opposite side of the treadle 29 another adjustablelink 3'! isattached, a clamp 38 being provided to effect this adjustability. To theleft of the fulcrum l2 a sleeve 39 is mounted in the base II, the sleevebeing externally screw threaded so that its position, either up or down,may be adjusted, the purpose of which adjustment will be set forthlater. A hand wheel 49 secured to the lower end of the sleeve,facilitates adjustment of the sleeve. Through the sleeve a rod 4|slides, a spring connection 42 attaching the rod to the link 31, theyielding action of which will be utilized for a purpose which willappear herein. On the rod 4| are the respective upper and loweradjustable stops 43 and 44 by means of which the rod is limited in itsmovement, as is readily seen in referring to the respective Figs. 1 and3 which show the upper and lower positions of the rod. A spring 45between the lower stop 44 and the table 28 normally retains the rod inelevated limited position shown in Fig. 1, while by stepping on treadle29 the rod 4| is, moved downwardly, the spring 45 is compressed, thestop 43 is brought to engage the upper end of the sleeve 39, and thespring 42 is stretched to permit treadle 29 to be moved completely toits floor contacting position. On the upper end of rod 4| a hook 46permits the attachment of the lower end of the spring I6 which is to betested, while a hook 4'! on a lug 48 on the balance arm and to the leftof the fulcrum thereof, permits of the attachment of the upper end ofthe spring to be tested.

I have now described the structure by means of which the testing ofclosed coil and even open coil springs may be accomplished, and whichoperation will be described as exemplary of one way in which the testermay be used:

Let it be assumed that the tester is prepared for use by having nospring l6 mounted in place for testing, then in moving weight i5 to thedotted line position shown, and, with the treadle lifted by springs 35and 45 so that weight 24 is lifted from the arm l3, in adjusting weightM so that arm l3 just balances nicely with its pointer I! at the zero(0) mark on the calibration 20. Then, the spring H; which is to betested, is hooked upon hooks 46 and 4?. Hand wheel 49 is then moved todraw the sleeve 39 downwardly, which operation takes up the looseness ofspring l6 on the hooks and also tends to cause arm l3 to move upwardlyon its right hand end, thereby bringing pointer I! to the right of thezero (0) mark on the scale 29. Weight I5 is now moved to the right untilthe coils of spring 16 just begins to break. The hand wheel 49 is thenadjusted to bring the pointer i! to the zero mark of the calibration.Since the spring has been designed to expand or stretch a certainprescribed amount when subjected to a specific load, the amount of thisstretch or expansion is obtained by loosening stops 44 and 43 andsetting 44 to abut the under or lower end of sleeve 39, while stop 43 isset in spaced relation to the upper end weight 24.

of sleeve 39 a distance which is the amount the spring is to stretchwhen in use and under tension. by the load for which it has beendesigned to function. This load is calculated and embodied in the formof weight 24 which, with the portion of arm l3 which lies to the left ofthe fulcrum, will be materially reduced in size because of the longerportion lying to the right of the fulcrum, the position of the weightbeing determined by the arm notch 21. Thus, with everything inreadiness, as has been described, the operators foot being placed ontreadle 29 will produce a simultaneous stretching of spring l6 and aremoval of platform 34 from beneath Since the spring stretch will be theamount for which the spring was designed, the simultaneous removal ofweight-supporting platform 34 so that the weight 24 will act, shouldresult in no movement of the pointer, theoretically speaking. However,since there is bound to be some variation in such theoreticalconditions, some degree of tolerance or deviation from the actuallyperfect performance is established. This, having been decided, will beestablished by the movement to either or both sides of the zero (0)mark, of the pointer. Any springs of a lot which have been made to meetthe designed requirements, which react to cause or permit the pointer tomove beyond the established limit of tolerance of the pointer movement,would naturally be rejected.

In other words, the principle upon which my tester has been designed tofunction, is that of coordinating a definite alteration in the length ofa spring, with a predetermined load with which the spring has beendesigned to balance.

The fixture, jig or attachment by means of which the compression springsmay be tested, and which is shown in Fig. 4, discloses that a plate 49which is suspended from hook 41 of the tester, supports a plate 59through two rods 58 and 52, and by means of which the lower end of thespring 5! is supported, while a plate 54 attached to book 46, supports aplate 53 by means of two rods 55 and 55.

In this manner opposed movement of the hooks, as when testing tensionsprings, will create the desired compression of the spring so that itmay be tested for rate as is done for expansion springs. No change inthe tester construction or operation is occasioned, it being merelynecessary, if desired, to adjust weight I5 to compensate for the weightof the attachment.

Having thus described my invention what I I claim is:

A coil spring tester comprising a base, a fulcrum supported above thebase, a balance arm supported on the fulcrum, a pointer on the arm inthe region of the fulcrum and extending normal thereto toward the base,a scale on the base associated with the pointer to indicate movementthereof, a weight adjustably mounted on one end of the arm to balanceit, means on the arm between the fulcrum and the weight for attachmentthereto of one end of the spring to be tested, a'

the arm, and coordinating mechanism adapted to operate the tensioner andweight lifter jointly, whereby simultaneously with spring tensioning thethird mentioned weight will be placed on the arm, said tensioner havingav movement causing the relative movement between the spring ends to bethat for which it was designed, said third mentioned weight beingproportioned to exert the load on the spring for which it was designed,and whereby upon the spring thusly becoming tensioned simultaneouslywith the application of the load thereto the pointer should assume aposition of rest substantially that of the prebalanced position of restestablished after adjustment of the second mentioned weight.

FRANK W. GASKINS.

